Bencycloquidium Bromide, also known as BCQB, is a muscarinic M3 antagonist potentially for the treatment of allergic rhinitis and chronic obstructive. Bencycloquidium bromide inhibits nasal hypersecretion in a rat model of allergic rhinitis. BCQB showed high affinity toward the M(3) receptor in Chinese hamster ovary (CHO) cells (M(3) pKi=8.21, M(2) pKi=7.21, and M(1) pKi=7.86); pA(2)=8.85, 8.71 and 8.57 in methacholine-induced contraction of trachea, ileum and urinary bladder, 8.19 in methacholine-induced bradycardia of right atrium in vitro, respectively.
